Many water systems are piped such that dead end segments exist in many places in the systems. Such would be the case for the piping going to the last house or other water user in a rural area served by the water system. Any piping beyond the last user will contain essentially stagnant water. Further, the water upstream of the last users will be stagnant to the extent that the last users do not consume the water. Stagnation of this water may permit increases in concentrations of biological organisms, because the organisms are not flushed out regularly. Furthermore, any chemical treatment provided in the water system to inhibit the proliferation of biological organisms may decrease in potency and ability to control such organisms when left in stagnant water. As the duration of stagnation of the water increases, and the free oxygen in the water decreases as a result of bonding in corrosion and of consumption by aerobic bacteria, anaerobic bacteria may increase in number, producing byproducts that may foul the water supply.
A further problem associated with the stagnation of the domestic water supply is the leaching of metals in the piping system into the water. Although in a municipal water system where the water is continually flowing this leaching may not be a concern, in dead end segments, the water may stand long enough for unacceptable quantities of metals to leach out into the water. Perhaps of greatest concern is the leaching into the water of lead that has been used in many systems in years past at joints in the piping system. Studies now clearly indicate that even small quantities of lead ingested by children can impose irreparable developmental damage to them. Iron, copper, and their oxides that leach into the water may affect the taste and appearance of the water, and in certain quantities, may render the water unfit for human consumption.
The water in dead end segments of municipal water systems needs to be flushed out periodically so that proper water chemistry is maintained in the dead end, and so that the last users' water supply does not become unusable by virtue of the increase in concentration of biological organisms, leachates and other impurities that may exist in stagnant water. In many municipal systems, this is accomplished by maintenance personnel periodically opening fire hydrants and other valves in the water system to allow a flushing water stream to purge the dead end segments. Unfortunately, however, with manpower limitations, and the inability to conduct such flushing on a rigorous schedule, the flushing operation may frequently be neglected. Moreover, the manual flushing is most likely to be accomplished during normal working hours, when water demand may be high and when significant flushing may tax the capacity of the municipal water system.
What is needed is an automatic flushing system that does not depend on a human attendant to begin and stop the flushing operation. The system should permit flushing at predetermined times and for predetermined durations, such that flushing may be accomplished off of the peak demand times on the municipal water system. Other flushing systems are known, such as that disclosed in U.S. Pat. No. 5,184,571 to Hostetler for use in watering systems for chickens or small animals. U.S. Pat. No. 5,476,118 to Yokoyama involves a system for eliminating stagnation in a super pure water system. These flushing systems are not adapted to provide a timed flush of dead end segments of municipal water systems.
It is accordingly on object of the present invention to provide an automatic flushing system suitable for installation in the supply piping of municipal water systems to accomplish preprogrammed flushing of the affected water piping. It is a further object of the invention to provide an automatic flushing system of relatively simple construction, and made of durable components. A further object of the invention is to provide an automatic flushing system that does not require an electric power source to be run to the location in which it is installed.